Straight wire lift pump

[DTR2214]

What would be wrong with straight wiring the lift pump? Instead of going through the OPS and other problems? The reason I ask is before I found this site my pump quit, I replaced pump and still didnt work, I didnt know what to do so I hooked it to a switched 12 volts.

[3bals]

It's more of a safety issue. If you got in a crash or something, your pump could keep running, spilling fuel out and feeding a fire. Not good. Did you check your fuses and/or the fuel pump relay?

Jody

[DTR2214]

Ive been running it this way for about three years, I just wondered why no one ever mentioned it here. But yes I checked fuses. Its probably the OPS, at the time I didnt know it controlled the lift pump. Im learning more every day !!!

[ChevyCowboy]

i think my truck is wired the same way the previouse owner did it. the way it is set up is a wire from the bat to the switch on the dash and then it is attached to some wireing on top of the block under the intake manifold i wish i could explain it better but dose that sound like it is close to what you did?

[DTR2214]

I wired mine to fuse panel, when I turn the ignition switch on its pumpin!

[ChevyCowboy]

is there any thing else that that switch could be turning on. If i start it without the switch being on it starts REALY ruff. also i have noticed that with that switch on it will idel about 2000 rpms higher the guy i bought the truck fom said to turn it on before i start it and then turn it off again but if it is for the lift pump that would make my IP have to work harder and destroy my Fuel milage im only getting maybe 14 or 15 any one have any ideas
ill try and put a picture up later of where the wire plugs in

[jifaire]

Uh... y'all DO realize that the lift pump is set up through that OPS switch for a reason, right? Jody had it right, up in post #2.

Safety concerns mandate that electric fuel pumps be hooked up that way (or patched through an impact sensor) so that, after you crash into something and a fire starts, your truck doesn't keep trying to put the fire out by pouring more diesel fuel on it until your battery runs out, or until you wake up and shut off the key or flip the switch.

The OPS shuts off the lift pump when oil pressure drops (ie, when the engine stops). That mey NOT coincide with the key being turned off.

A new OPS is only $30. How much is your daughter worth, should she happen to be strapped into her car seat some day when somebody else hits you and sets off a bad chain of events?

Think, people, please. You only get one chance to make the right decision... that's BEFORE the accident. After that, you only get to WISH you had.

[DTR2214]

Yes Daddy, I will fix it.

[jifaire]

Yes Daddy, I will fix it.


Oops. Appears I overdid it. Sorry.

Seriously, I qualify everything like this by saying that I believe in YOUR ability to drive safely and stay out of a crash... but I don't believe the same for everyone else. It only takes one moron to make an accident.

It's like saying "sure, I believe you could pull your fifth wheel without trailer brakes. I know you would slow down in lots of time, stay well within safe speed limits, and gear way down on hills.."

But that's assuming you're travelling on an empty road. I've driven over a million miles accident-free, and I gotta say that I've spent a bunch of that time in sheer disbelief at the stupidity of some drivers. Defensive driving only takes you so far.

As much as I don't want to be condescending, I'd feel bad if something happened to you and I hadn't said anything beforehand.

Jim

[DTR2214]

Im just playing, I see what your saying and I think I will fix it the proper way, if not for myself, for the safety of others. I honestly didnt know it is a safety feature or I wouldnt have straight wired it. Thanks for the info.

[94K30]

If you find that it still doesn't work with a new OPS, check the harness that plugs into the OPS. Mine drove me crazy, I changed out the lift pump, the relay and the OPS, and it still did not run. The female connectors in the weather-pac connector had spread and weren't making contact..... Changing the connector did the trick.....

[ChevyCowboy]

well if this switch is turning the Lift Pump on then i will get i fix deffinatly dont want to be unsafe when fule is conserned

here are the pics of the wire it is the bigger one that is wraped around the trottle cable

[ChevyCowboy]

dose anyone know what that wire is running my truck is really stating to start wired and i think that may have something to do with it any ideas would realy be appriciated cause i dont have a clue:confused:

[JD_countryboy]

I'm having a hard time tryin to decipher that pic. Can you get a better pic? You say by flipping the switch that is connected to that wire, your truck will idle 2000 rpms higher? If that is the case, i'm guessin that the previous owner replaced the cold idle step up soleniod. it is located on the right side of the pump (looking over top of engine from front) on the top of pump directly over throttle lever. Its puropse is to add rpms, usually like 200-300 from what i was told, to aid in faster warmup. My solenoid was round, and junk so i never put it back on. chevy stealersip was the only place i could find one, $180.

[JD_countryboy]

Ok wait a sec, i took another look, and got it to enlarge finaly. The single green wire to the right should be hooked to the cold idle step up solenoid. I see the bigger red wire from the throttle cable down. The front terminal on that (left) side of the pump should be the fuel shutoff solenoid. The rear terminal is the cold start timing advance piston. Looks as if the larger red wire is hooked to the rear terminal, along with two green wires. THe green wires were factory cold start timing advance piston. I wouldn't know why they would have kept them hooked up and add the extra red wire. When you put power to the cold start timing advance piston you advance the timing. it should cause little to no rpm increase though. Mine doesn't. The factory sensor that controls that on mine is junk, always advance timing, so i just added wire and put it on a togle switch in the cab for now. (that was another late sunday night find/fix). I'd say its the cold start ting advance piston. After I got the pics to enlarge, they are pretty good pics.

[ChevyCowboy]

thanks so it sounds like that has nothin to do with my starting problem im ganna have to do some more looking into that im thinking it may be the glow plugs but i need to test them yet. so how much will it advance the timeing with that switch on i do notice that with it on it make more smoke. Will running with that on all the time hurt any thing i was going to advance my timing some anyway so is that doing it for me? the old owner said to flip it on before start up and then off after the truck was started

[JD_countryboy]

I'm not sure the exact degrees. I'd have to get my gm manual back and look it up. Driving it on all the time would be like manualy advancing the pump. Not good if it gets too far. From what i hear 6.5 don't like to have the pumps too far advaced from spec. But i really don't know, havent had much experience with them yet. The one thing you will notice the most is it will rattle more, sound louder.

[ChevyCowboy]

hey JD
i talked to the previous owner and he said it is for the cold start advance piston so you got it right. i happened to come across his number so i gave him a call he also told me that at 192000 miles he put in a rebuilt injector pump, new lift pump and new stock injectors. the truck is at 229000 now so i think the only thing i have to worry about is the glow plugs

[grancito]

is there any thing else that that switch could be turning on. If i start it without the switch being on it starts REALY ruff. also i have noticed that with that switch on it will idel about 2000 rpms higher the guy i bought the truck fom said to turn it on before i start it and then turn it off again but if it is for the lift pump that would make my IP have to work harder and destroy my Fuel milage im only getting maybe 14 or 15 any one have any ideas
ill try and put a picture up later of where the wire plugs in
You have manual IP, and when there is no lift pump pressure, it advances the timing, hence increased revs and rough running. When the engine is cold, a soleniod opens to bleed fuel back to the tank to drop the pressure so that the timing is advanced and to remove air from the system. The lift pump has to run all of the time.

[JD_countryboy]

Thanks for clearing that up grant. I knew it was supposed to change timing somehow, but didn't know how exactly. Now i do.

[JD_countryboy]

ok, if that is how it works, then somethings wrong with mine. There is always power to my cold strat timing advance piston. ALWAYS. Always have power evenwhen temp gauge reads 180* so i just added some wire and put a toggle switch in the cab. Switch gets its power from factor connector that used to plug onto solenoid. used a spade conector and just slid into factory connector, so if i ever fix the problem, i can just plug it back like fatory. I never use it though, cause all it does is make the engine rattle more. no more rpms, no rough running, just rattle more, like timing is too far advanced. it starts pretty much the exact same with the switch sendin power to the solenoid, or off. I used a glow toggle switch to monitor when the switch is on and it has power. So i just dont use it. Runs fine without using. Any ideas?

[grancito]

I disconnected that cold start bleed/advance solenoid and throttle soleniod 10 years ago when the temperature sensor failed that controls it. Doesn't get cold here so not needed.